Two studies are presented to develop procedures for the modification of weight in overweight 5 to 7 year old children. Both studies involve random assignment of overweight children to one of four groups: a no treatment control, nutritionally based eating regulation, activity increase, and eating plus activity procedures. In Study I parents will be trained to implement these procedures at home. Similar procedures will be used in Study II, implemented in a modeling format, such that parents are required to model appropriate eating and/or exercise behaviors for their overweight child to imitate. Treatment will be in effect over a twenty week period in both studies, with seven month follow-up. Results will suggest the relative importance of eating control versus activity increase in the treatment of childhood obesity, as well as indicating the best way to implement these techniques. Effects of the child-based health habit change on other members of the family will be assessed. The procedures described could be important in prevention of adult overweight, by teaching appropriate eating and exercise habits.